Book contents
- Frontmatter
- Contents
- List of Contributors
- PART 1 Basic Mechanisms of Genome Rearrangement in Bacteria
- 1 Mechanisms of homologous recombination in bacteria
- 2 Introduction to site-specific recombination
- 3 Site-specific recombination by the serine recombinases
- 4 Mobile introns and retroelements in bacteria
- PART 2 Horizontal Gene Transfer and Genome Plasticity
- PART 3 Biological Consequences of the Mobile Genome
- Index
- Plate Section
- References
4 - Mobile introns and retroelements in bacteria
Published online by Cambridge University Press: 06 August 2009
- Frontmatter
- Contents
- List of Contributors
- PART 1 Basic Mechanisms of Genome Rearrangement in Bacteria
- 1 Mechanisms of homologous recombination in bacteria
- 2 Introduction to site-specific recombination
- 3 Site-specific recombination by the serine recombinases
- 4 Mobile introns and retroelements in bacteria
- PART 2 Horizontal Gene Transfer and Genome Plasticity
- PART 3 Biological Consequences of the Mobile Genome
- Index
- Plate Section
- References
Summary
Introns and retroelements are hallmarks of eukaryotic genomes, but they are also found in bacteria. Here the different types of bacterial introns and retroelements are summarized, including group I introns, group II introns, archaeal bulge-helix-bulge (BHB) introns, intervening sequences (IVSs) in rRNAs, retrons, and diversity generating elements (DGRs). Except for the retroelements, these elements are evolutionarily unrelated, but nevertheless share intriguing properties. The elements all appear mobile within and among bacterial genomes, and in general, do not have clear phenotypic consequence to their host cells. It is possible that introns and retroelements spread from bacteria to eukaryotes as selfish DNAs or were present in the common ancestor of bacteria and eukaryotes.
INTRODUCTION
Introns and retroelements are typically considered components of eukaryotic genomes, because they were discovered in eukaryotes and are particularly abundant in higher eukaryotes. The human genome, for example, contains roughly 200,000 introns and nearly 3 million retroelements (including SINEs), dwarfing the number of functional genes, which are estimated at 30,000 (International Human Genome Sequencing Consortium, 2001). Together, introns and retroelements make up nearly half of the human genome and constitute the major types of “junk DNAs.”
In bacteria, the major types of “junk DNAs” are transposons and prophages, which can constitute anywhere from <1% to 7% of a genome (e.g., Glaser et al., 2001). Introns and retroelements are comparatively rare in bacteria, but they have generated substantial interest because of their parallels to eukaryotic introns and retroelements.
- Type
- Chapter
- Information
- The Dynamic Bacterial Genome , pp. 121 - 148Publisher: Cambridge University PressPrint publication year: 2005
References
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